I never suggested that an unlikeable person has in any way 'brought it on themselves', @Jannt86. I think you're relating my question back to the OP's post, whereas I was only responding to yours.
But, since you ask, I think 'likeability' is pretty subjective -- no one is universally likeable. I'm certainly not, though I have good, lasting friendships that enrich my life. Equally, I'm not everyone's cup of tea.
I do think, though, that you can learn social skills, even if you were raised with poor friendship models and some deeply odd ideas about human relationships.
My parents gave me very odd, unhelpful childhood scripts about friendships. I've talked about them on here before under previous user names. My father is not NT and his only 'friends' are people he's never met in the flesh, who live on the other side of the world and with whom his interactions are purely formal conversations about the weather and hobby-related stuff. He knows nothing about these people beyond their names and equipment types.
My mother is a chronic people-pleaser who chooses to be a shoulder to cry on for the unwell and unlucky because it makes her feed needed, and then gets very bitter when they don't invite her to 'fun' stuff when they're feeling better. I don't think she has a single real friend in the world, because her only contribution to these relationships is to abase herself to the other person's needs and nod along with whatever they're saying -- there's nothing of herself in there. Her phone calls with them can last an hour in which she sounds like a Samaritan.
I had to learn as a young adult how to negotiate friendships, after I'd realised how skewed my parents' ideas about them were.
I think it's a realisation that would benefit many Mners who struggle with friendships, whose posts express bafflement that no one invites them to things when they're 'been there for them' for years. Positioning yourself as a service provider/permanently available listening ear or shoulder to cry on/rescuer is no way to make friends.